The Section of General Surgical Pathology provides clinical surgical pathology diagnostic services to the NIH Clinical Center, and thereby to the entire NIH community. The diagnostic modalities utilized include hematoxylin and eosin-based histology, and adjunct studies such as immunohistochemistry, molecular genetic studies, and tissue-based fluorescence in situ hybridization. The breadth of disease processes encountered by clinicians in this Section is wide, and includes cancer, benign tumors, infectious diseases, degenerative diseases and the aging process, developmental disorders, diseases of the heart and circulatory system, and genetic diseases. Many of the specimens evaluated derive from unique populations of patients with rare or even undiagnosed diseases. Accordingly these clinical tissues from biopsies and surgical resections, along with the corresponding patient clinical information, comprise a resource rich for collaborative research projects for the clinical staff in the Section. In addition, they are utilized as an essential component in the training of Anatomic Pathology residents in the Laboratory of Pathology's well-regarded ACGME-accredited Training Program. During the year we participated in neurosurgical research project related to hybrid schwannomas, studies on adrenal carcinomas on IL13 receptor expression, and in projects on mesothelioma xenografts and BAP1 mutations. We also examined biology of PD-L1-positive colon cancer, and NTRK and ALK fusions in colon carcinoma and their diagnosis by immunohistochemistry. During the last years, we have studied PDL-1 positive colon cancers, pathology and genetics of non-cutaneous melanoma, and fusion sarcomas and carcinomas, especially, colon carcinoma finding infrequent NTRK alk ALK gene involving fusions and characterized those tumors in detail.